The Aldens' dog, Watch, comes across a mysterious box with a note inside, a box that is part of a game called Geocaching. Henry, Jessie, Violet, and Benny join the game but soon suspect one of the members of the geocaching club is a thief.

When the children uncover a strange puzzle in a friend's back yard, it's the start of a "spy game" leading to gold. But first they must make sense of an old photo and a riddle, and learn just who is behind this mystery within a mystery.

Henry, Jessie, Violet, and Benny discover that some of the clues to the Great Detective Race are fake and set out to find out who is trying to ruin the race.

The Aldens discover there's nothing more fun than a drive-in movie. But pranks and other odd things are happening at the Diamond Drive-In, and late at night, a ghost is seen walking around the empty lot. Is the old theater really haunted?

When Henry's magic teacher, The Amazing Arthur, goes missing right before the Greenfield Magic Shop's annual magic show, Henry and his sibilings look into Arthur's disappearance.

The four Alden children, aged six to fourteen, volunteer at the new recycling center in town, and help uncover who is breaking in and making a mess each night.